pip is most nutritious when used with virtualenv. One of the reasons pip doesn’t install “multi-version” eggs is that virtualenv removes much of the need for it. Because pip is installed by virtualenv, just use path/to/my/environment/bin/pip to install things into that specific environment.
To tell pip to only run if there is a virtualenv currently activated, and to bail if not, use:
pip was originally written to improve on easy_install in the following ways:
pip doesn’t do everything that easy_install does. Specifically: